This paper aims at probing into the topic of power units' operation and dispatch based on Carbon Dioxide (CO(2)) trading scheme. The trading cost of CO(2) emission is embedded into the traditional economic dispatch model, which will be solved by the New Particle Swarm Optimization (NPSO). By considering the CO(2) trading scheme, the influences of the various strategies for unit's dispatch are simulated and analyzed in this paper. The proposed method, NPSO is developed in such a way that PSO with Constriction Factor (PSO-CF) algorithm is applied as a based level search. NPSO introduces two operators, "Random Particles" and "Fine-Tuning" into the PSO-CF algorithm to improve the drawback of searching global optimum and make the search method more efficient at the end of search. The efficiency and ability of NPSO is demonstrated by the six generating units. Simulation results indicated that reasonable solutions provide a practical and flexible framework for power sectors. They can be also used for generating alternatives and thus help decision makers to obtain the goals of minimal operation cost under their desired emission's policies. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.